Sigh...
OPTRONICS!
http://www.optronicsinc.com/competition.htm
Why reinvent the wheel when these are so cheap? Look at the QH-8CC. They are small, look right at home on bike, handle a 50 lamp, are easy to fashion mounts for, and CHEAP, about $16 per PAIR. You can order directly from Optronics if you can't find them locally. 50W is more than most people want to carry battery for, so replace them with a 20 or 35W. They have slots for ventilation. I don't tape over them, but I do make a little "hood" with tape to keep rain from dripping straight in. This has worked for a couple of years, including some very rainy rides.
FWIW,
Raymond
Originally Posted by Multibiker
The housings look really good. It's always a problem for us homebuilders to find a cheap suitable housing. The first two beam shots are good, they show how bright the 35W spot is. The third shot needs something to compare, like a car headlight.